DESCRIPTION
XALOC aims to provide the present and future Structural Biology groups with a flexible and reliable tool to help in finding solutions for structures of macromolecules and complexes. The beamline copes with a broad variety of crystal sizes and unit cell parameters, and allows both wavelength dependent and independent experiments.
USER ACCESS STATUS
The Call for proposals for 2024 cycle is closed:
- Opening: July 3rd, 2023
- Deadline: September 4th, 2023, 14:00 CEST
Call for Proposals for 2024-I cycle for BL13-XALOC will cover all the year for BAG proposals.
APR 2024: Unattended automatic data collection is currently available.
MAY 2023: A new Pilatus3 X 6M detector 100Hz installed at XALOC.
Continuous access to XALOC is available anytime throughout the year, see the users call information page
Remote data collection is fully operative
Important note: During 2024, ALBA will also cover the dewar transport for all EU users (only for remote access experiments).
To submit a proposal go to:
http://useroffice.cells.es/
More information about the Call:
http://www.cells.es/en/users/call-information
More information about funding rules:
https://www.cells.es/en/users/user-funding
- Check the Preparing you Experiment page to see relevant information about administrative steps and technical requirements!
MXCuBE and ISPyB-EXI (https://ispyb.cells.es/) are already available. Follow the ISPYB-EXI user manual here
XALOC supports both SPINE (EMBL/ESRF) pucks and Unipucks, which allow fast sample interchange.
Our CATS robot dewar can host up to three SPINE (EMBL-ESRF) pucks and six Unipucks.
- Please include the reference to the beamline paper in your publications containing data collected at XALOC beamline:
J. Juanhuix, F. Gil-Ortiz, G. Cunı, C. Colldelram, J. Nicolas, J. Lidon, E. Boter, C. Ruget, S. Ferrer and J. Benach, "Developments in optics and performance at BL13-XALOC, the macromolecular crystallography beamline at the Alba Synchrotron", J. Synchrotron Rad. 21, 679–689 (2014).
DOI:10.1107/S160057751400825X
STATUS
The beamline is under user operation from 18 July 2012. Three calls for proposals have been completed so far.
TECHNICAL SPECIFICATIONS
Photon Energy (Wavelength) range | 4.6-23 keV (2.6-0.52 A) |
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Flux at sample | > 2·1012 photons/s/250mA at sample (measured) |
Energy resolution (DE/E) | 2·10-4 |
Beam size at sample (FWHM) | Adjustable 50-300 (H) x 6-100 (V) μm2 |
Beam divergence at sample (FWHM) | < 0.5 x 0.1 mrad2 (HxV) |
The beam size will be fitted to the crystal dimensions by (a) adjusting the focus of the mirrors along the beam path, and (b) having two beamline operation modes: focused and unfocused.
In the unfocused configuration, one or both mirrors are removed from the photon beam path, resulting in a very limited beam divergence, less than 0.03 mrad vertically. This mode can be especially useful for large macromolecular complexes with large unit cell parameters. In the focused configuration both mirrors can focus the beam to 50×6 µm2 FWHM (H×V) on small or microcrystals, while at the same time retaining a small and useful vertical divergence (0.1 mrad). In addition, the mirrors allow variable focusing (de-focusing) if matching the size of the X-ray beam to the dimensions of the crystals, or if focusing at the detector (which can be placed at any distance between 80 mm to 1300 mm from sample) is required. In this case, the beam size at the position of the sample can range from 50×6 µm2 up to 300×300 µm2 (H×V). In order to avoid x-ray beam deformations caused by the optics when defocusing, slope errors of the mounted mirrors have been reduced to 70 nrad RMS and the monochromator crystal can work close to the zero-expansion temperature of Silicon (124 K).
ENDSTATION
The end-station is based on two positioning tables that support the detector and the diffractometer (and the beam-conditioning elements). Both tables have been developed in-house.
Beam conditioning elements
These are the elements immediately in front of the sample, they consist of 12-foil attenuators, x-ray position monitors, slits, slow and fast shutters, and a kapton window.
- Position monitors: both 4-quadrant CVD diamond (DECTRIS)
- 12-foil attenuators (ESRF type)
- Fast shutter (FPS400 CEDRAT)
- Slits (JJ-Xray ESRF type)
Diffractometer (MD2M - Maatel)
Where the sample is to be rotated for data collection. The system includes a high accuracy omega axis (and a mini-kappa) and an on-axis viewing system.
- On-axis viewing system: a digital camera (Bzoom) allows instantaneous zooming of the sample.
- 2 μm sphere of confusion
- mini-kappa
- XYZ movable beam stop (in-house design)
Automatic Sample Changer (CATS - IRELEC)
The 6-axis robotic arm is used to manipulate both cryosamples and room-temperature crystallization plates. The Dewar is able to store a maximum of 108 cryosamples.
- Robotic arm to mount/unmount SPINE pins
- The liquid N2 Dewar is able to store up to 108 samples
- Ability to scan Greiner, MRC and Fluidigm crystallization plates
- Barcode reading
- Supports EMBL/ESRF and Unipuck standards
Fluorescence detector
XFlash Detector 410-SA - Bruker to allow anomalous scattering experiments.
PILATUS3 X 6M (100Hz) - Dectris
The main data collection detector is capable of recording up to 100 images per second.
- 425 x 435 mm active area, 6 Mpixels
- 1 Million counts dynamic range (20 bits)
- Delivery May 2023
- Virtually noise free
- Sensor thickness 1000um
- Quantum efficiency at 17.5 KeV 76%
Cryostream: 700 series - Oxford Cryosystems
- 100K to 400K operation
- 0.1 K stability
Crystal washer
Norhof model 915 LN2 pump allows to clean the ice formed on the crystal surface through a liquid nitrogen stream.
Cryoshutter
Allows remote crystal annealing of the crystal.
SOURCE
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In-vacuum undulator (IVU21). The photon source of the XALOC beamline is an in-vacuum undulator placed in a medium straight section of the ALBA storage ring. The undulator is fully tunable within the useful energy range for Macromolecular Crystallography experiments (4.6 - 23 keV). Parameters
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LAYOUT
Channel-cut Si(111) + KB focusing mirrors
The main XALOC optical elements are: a diamond window (not shown in figure); a removable diamond filter (which could also be used as a Laue monochromator); a channel-cut monochromator; and a Kirkpatrick-Baez (KB) focusing system.
Monochromator
Type | Si(111) channel-cut, cryocooled |
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Gap between crystals | 6 mm |
Absorbed power | <100 W (in working conditions) 460 W (in worst-case conditions) |
Bragg axis resolution (measured) | <1 µrad (<0.2 arcsec) |
Bragg axis stability (measured) | <1 µrad/1 hour |
KB Mirrors
Vertical Focusing Mirror | Horizontal Focusing Mirror | |
---|---|---|
Type | Elliptically bent mirror | Elliptically bent mirror |
Substrate | Si | Si |
Coating material | Si, Rh, Ir | Si, Rh, Ir |
Angle of incidence | 4.1 mrad | 4.1 mrad |
Optical length | 300 mm | 600 mm |
RMS slope error (bent, measured) | <0.1 µrad | <0.1 µrad |
Other optical elements include white beam attenuators, slits, photon shutter, fluorescent screens and x-ray beam positioning monitors.